Update of barbuk theme (add modular blocks)

[BarbUk]

Description

This is a complete rework of my theme.

Motivation and Context

I'm using more tools at work or for personal usage that need context in my shell:

• ruby version
• terraform
• aws / scw profil

The theme is the same, but with more flexibility.
You can now configure it to display different information by setting BARBUK_PROMPT env variable.

How Has This Been Tested?

All new block are inspired from base theme or powerline theme.
I use the theme to work, it's was tested in real work condition :).

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• If my change requires a change to the documentation, I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• If I have added a new file, I also added it to clean_files.txt and formatted it using lint_clean_files.sh.
• I have added tests to cover my changes, and all the new and existing tests pass.

[BarbUk]

Just a precision:

• Theme display does not change
• The rework is only to make it more customizable / modular

[BarbUk]

I changed the title to make it less scary :)

The major thing is:

• if people are using this theme, it will not change after update
• the theme is now modular and can be configured with BARBUK_PROMPT env.

BARBUK_PROMPT="git-uptream-remote-logo ssh path scm python_venv ruby node terraform cloud duration exit"

Feedback and review are welcome.

[NoahGorny]

LGTM!
Thanks for contributing @BarbUk !